1. Field of the Invention
The present invention relates to a motor that has added improvements to reduce vibration generation and magnetic leakage as well as an articulated serial robot that has a motor built in. In addition, the present invention relates to a substrate loader that includes an articulated serial robot, with added improvements to reduce or restrict vibration and increase high speed handling performance, and/or as well as an exposure apparatus equipped with the substrate loader.
2. Description of the Related Art
FIG. 14 illustrates a formation-related apparatus and control system overview of an entire optical system of an electron beam exposure apparatus of a projection exposure system.
An illumination optical lens barrel 201 is arranged at the upper portion of electron beam exposure apparatus 200. A vacuum pump (not shown in the drawing) is connected to the optical lens barrel 201 and performs vacuum exhaust within the lens barrel.
An electron gun 203 is arranged at the upper portion of the lens barrel 201 (including the mask chamber), and an electron beam is irradiated downward. A condenser lens 204, an electron beam deflector 205 and a mask M are arranged in sequence below the electron gun 203. The electron beam irradiated from the electron gun 203 is converged by the condenser lens 204 as it is sequentially scanned in the horizontal direction in FIG. 4 via the deflector 205, and illumination of the small regions (subfields) of the mask M within the visual field of the optical system is performed. The above-described illumination optical system has a beam formation aperture and a blanking aperture, etc. (not shown in the drawing).
The mask M is secured via an electrostatic suction, etc., to a chuck 210 provided at the upper portion of a mask stage 211. The mask stage 211 is mounted on a mount body 216.
A drive apparatus 212 is connected to the mask stage 211. The drive apparatus 212 is connected to a control apparatus 215 via a driver 214. In addition, a laser interferometer 213 is installed on the mask stage 211. The laser interferometer 213 is connected to the control apparatus 215. Accurate positional information of the mask stage 211 calculated by the laser interferometer 213 is input to the control apparatus 215. A command is then sent from the control apparatus 215 to the driver 214, and the drive apparatus 212 is driven.
A wafer chamber 206 (vacuum chamber) is shown below a mount body 216. A vacuum pump (not shown in the drawing) is connected to the wafer chamber 206, and the vacuum pump evacuates the inside of the chamber.
A projection lens 224, a deflector 225, etc., are arranged in the projection optical system lens barrel (not shown in the drawing) inside the wafer chamber 206. In addition, a wafer stage (precision equipment) 231 is mounted on the lower surface of the wafer chamber 206 that is further below. A chuck 230 is provided at the upper portion of the wafer stage 231, and a wafer W is secured via an electrostatic suction, or the like.
The electron beam that has passed through the mask M is converged via projection lens 224. The electron beam that has been converged by the projection lens 224 is deflected by deflector 225, and the image of the mask M is resolved at the prescribed position on the wafer W. The projection optical system also has various types of aberration compensation lenses, contrast apertures (not shown in the drawing), etc.
A drive apparatus 232 is connected to the wafer stage 231. The drive apparatus 232 is connected to the control apparatus 215 via a driver 234. In addition, a laser interferometer 233 is installed at the wafer stage 231. The laser interferometer 233 is connected to the control apparatus 215. Accurate positional information of the wafer stage 231 calculated by the laser interferometer 233 is input to the control apparatus 215. Based on this, a command is sent from the control apparatus 215 to the driver 234, and the drive apparatus 232 is driven.
FIG. 15 is a plan view showing a wafer conveyance mechanism within a common wafer chamber. In FIG. 15, a wafer stocker 261 in which a plurality of pre-processed wafers is accommodated and a wafer loader 250 are arranged inside the wafer chamber 206. The wafer is conveyed from the wafer stocker 261 onto the wafer stage 231 via the loader 250, mounted on the wafer stage 231 and supplied to an exposure transfer. The loader 250 has an arm rotatably linked.
In the aforementioned loader 250, the wafers are transported one at a time from the wafer stocker 261 to the wafer stage 231 via an end effector provided on the arm. In addition, the wafers are also conveyed one at a time when returning the wafers from the mask stage 231 to the mask stocker 261 after the transfer has ended.
When the substrate loader is operated at a high speed, the positional accuracy and stabilization times of the end effector decreases. This occurs because vibration increases when operating at high speed, since rigidity of the mechanism portion of the substrate loader does not increase. To deal with the foregoing problem, the residual difference between the actual sample position and the target position is obtained, and the end effector is positioned according to the obtained value. The end effector is positioned according to a rotary encoder and microrotation motor, which is the drive source, provided within the joint portion of the arm equipped with that end effector. First, the rotation angle of that arm is detected by the rotary encoder, and the position of the sample on the end effector is obtained from this rotation angle. At this time, a detection cycle of approximately five times the characteristic frequency of the mechanism portion is generally required. Then, a fine adjustment operation amount is calculated from the deviation between the actual sample position and the target position, a command is provided to the microrotation motor, and the detected rotation angle is fed back.
In the foregoing type of exposure apparatus that uses an electron beam, measures are implemented to control the magnetic field fluctuation that is the cause of the deflection of the electron beam and the vibration generation that causes pattern accuracy to drop. For example, an electromagnetic linear motor with superior controllability and for which magnetic shielding has been implemented is used as the drive source of the wafer stage or the mask stage. In addition, the wafer and mask conveyance sequence is being reviewed, and progress is being made so that adverse effects on exposure accuracy can be avoided.
However, even when the aforementioned measures are implemented, when the wafer conveyance operation is performed during exposure, vibration is generated due to the driving of the conveyance robot (loader), a magnetic field is generated from, for example, the motor built into the robot, and pattern accuracy is reduced. That is, when the drive shafts of the arms of the loader are rotated, a reaction force is applied to the stators of the rotors. In addition, an electromagnetic drive system rotation motor is used as the motor that drives the arms of the loader. Although such an electromagnetic rotation type motor is typically compact, lightweight, energy efficient, and able to be controlled, AC magnetic field leakage from the coil generally occurs and/or DC magnetic field leakage from the magnets generally occurs. In addition, the material point shifts and vibration occurs due to arm movements, such as extension, raising, and/or lowering.
In addition, an arm equipped with an end effector positioned at the extreme distal end of the substrate loader vibrates very little due to movement and rotation; therefore it is necessary to standby until the vibration has settled. Accordingly, handoff of the wafer during the standby time is not possible and the throughput of the apparatus decreases.
For at least the foregoing reasons, it was not possible to simultaneously perform the wafer conveyance operation and the exposure operation. Further, in the wafer conveyance operation, the wafers are conveyed one at a time by a loader, which causes a decrease in the throughput of the exposure apparatus.
In this regard, to ensure pattern accuracy and/or improve the throughput, countermeasures are needed that control leakage magnetic fields and/or the generation of vibration from the robot for wafer conveyance so that it is possible to perform the exposure operation and the wafer conveyance operation together or simultaneously.